The fabrication of an integrated circuit, display or disc memory generally employs numerous processing steps. Each process step must be carefully monitored in order to provide an operational device. Throughout the imaging process, deposition and growth process, etching and masking process, etc., it is critical, for example, that temperature, gas flow, vacuum pressure, chemical gas or plasma composition and exposure distance be carefully controlled during each step. Careful attention to the various processing conditions involved in each step is a requirement of optimal semiconductor or thin film processes. Any deviation from optimal processing conditions may cause the ensuing integrated circuit or device to perform at a substandard level or, worse yet, fail completely.
Within a processing chamber, processing conditions may vary. The variations in processing conditions such as temperature, gas flow rate and/or gas composition greatly affect the formation and thus the performance of the integrated circuit. Using a substrate-like device to measure the processing conditions that is of the same or similar material as the integrated circuit or other device provides the most accurate measure of the conditions because the thermal conductivity of the substrate is the same as that of the actual circuits to be processed. Specifically, wireless substrate-like devices are preferred over wired substrate-like devices because wired substrate-like devices are cumbersome to use and latency associated with such devices is non-ideal. Gradients and variations exist throughout the chamber for virtually all process conditions. These gradients therefore also exist across the surface of a substrate. In order to precisely control processing conditions at the substrate, it is critical that measurements be taken upon the substrate and that the readings are available to an automated control system or operator so that the optimization of the chamber processing conditions can be readily achieved. Processing conditions include any parameter used to control semiconductor or other device manufacture or any condition a manufacturer would desire to monitor.
In order for such wireless substrate-like metrology devices to function in high temperature environments (e.g., temperatures greater than about 150° C.), certain key components of the device, such as thin batteries and microprocessors, must be able to function when the device is exposed to the high temperature environment. Many device fabrication processes operate at temperatures greater than 150° C. For example, a back AR coating (BARC) process operates at 250° C.; a chemical vapor deposition (CVD) process may operate at a temperature of about 500° C.; and a physical vapor deposition (PVD) process may operate at about 300° C. Unfortunately, batteries and microprocessors suitable for the requirements for such a device typically cannot withstand temperatures above 150° C. While wired substrate-like devices may be configured to withstand temperatures above 150° C., they are not preferred for the reasons stated above.
An additional challenge faced by such wireless substrate-like metrology devices is minimization of the device profile. Such devices should keep a profile of 5 mm or less above the top surface of the substrate in order to fit into various process chambers.
Conventionally, temperature-sensitive wireless metrology device components (e.g., batteries, CPU, etc.) are shielded from high temperatures using insulating modules. U.S. patent application Ser. No. 12/690,882, filed Jan. 20, 2010 discloses one such insulating module. Such an insulating module comprises a component encapsulated on both sides by an insulating layer (e.g., ceramic or other microporous insulating material), the combination being further encapsulated on both sides by a high specific heat enclosure. The insulating module may then be bonded to the substrate, attached to the substrate by way of kinematic supports, or formed within the substrate.
While such insulating modules do achieve the goal of shielding temperature-sensitive wireless metrology device components, they exhibit several undesirable characteristics that make it non-ideal. For one, these insulating modules are extremely complex to manufacture due to the need to ensure a vacuum between the component, insulating layer, and high specific heat enclosure. Additionally, these insulating modules have a high chance of collapsing when exposed to atmospheric pressure due to the presence of low pressure within the module. Further, the use of insulating machinable ceramic and micro porous insulation such as Microsil has the disadvantage of generating contaminating particles that may affect the performance of the processing chamber. Microsil is a specific name for a micro porous insulation material available from Zircar Ceramics, Inc. of Florida, N.Y. Additionally, these materials are also quite difficult to construct and attach, causing added complexity in assembly as well as reliability issues.
It is within this context that embodiments of the present invention arise.